Posted
by
samzenpus
on Wednesday May 21, 2014 @10:11PM
from the give-it-a-try dept.

greg65535 (1209048) writes "Following the trend of on-line coding playgrounds like JSFiddle or CodePen, Google researchers unveiled the first browser-based, GPU-powered Quantum Computing Playground. With a typical GPU card you can simulate up to 22 qubits, write, debug, and share your programs, visualize the quantum state in 2D and 3D, see quantum factorization and quantum search in action, and even... execute your code backwards."

Would a simple botnet be able to easily crack all encryption crackable by quantum computing, or are there better ways to go at it given a botnet?

Yes it is crackable using a bother simulating a quantum computer, in the same sense that you would be able to simulate a quantum computer solving the traveling salesman problem by using a botnet. Or by using a massively parallel supercomputer.

That is to say, the quantum computer simulation is Turing computable. This really doesn't help for anything more than trivial problems, much like pointing out the Halting Problem is decidable if you "simply" observe the Turing machine for the appropriate Busy Beaver [wikipedia.org] function's number of execution steps.

More succinctly, the simulation would gain you nothing over a direct parallel processing attack on the key space, and in fact the quantum computer simulation would add execution overhead that would reduce efficiency compared to straightforward brute force attacks.

For a regular computer to be reversible it needs reversible logic gates. For example, a standard XOR gate loses one bit of information, so given the output you cannot construct the input perfectly (as there are two possible inputs for each output).